Advances in computer technology in general, and database search and retrieval techniques in particular have given birth to various forms of transaction processing methods to implement diverse types of applications, such as credit authorization and identity verification. Typically, these transactions involve transmission of a search key to a database which returns to the inquirer a field or a record of limited size. In general, transactional communications can be described as short and bursty traffic that requires secure, rapid and cost effective access to a validation or authorization database. In response to this need of the marketplace, two major types of communications access arrangements have been devised.
One popular access arrangement for transactional processing is a multidrop private line connected directly to a database or a front-end processor attached to the database which polls, on a regular basis, terminals connected to a cluster controller at each drop of the line. Analog multidrop private lines are arguably cost effective for large businesses with a great number of users because they take advantage of economies of scale due to concentration of traffic generated by a great number of terminals at clustered locations. However, for small to medium size businesses with a limited number of users, the monthly leasing cost of a multidrop private line can be prohibitive.
Even for large businesses, multidrop private lines present various disadvantages that greatly outweight their perceived cost effectiveness. For example, the known unreliability of multidrop private lines creates a need for expensive redundant circuits and networking hardware that also need to be managed and administered. In addition, systems that use multidrop private lines a) lack flexibility in terms of network reconfiguration, and b) confine users to a limited choice of vendors for hardware and software, resulting in a major handicap in the age of open systems. Finally, unlike switched communications lines, multidrop private lines are not ubiquitously available.
Another access arrangement for transactional processing involves the use of a switched communication line. In this arrangement, terminals equipped with modems, autodialers, magnetic stripe readers and the like, initiate data calls automatically over a communication switching system to establish communications with a database in response to a specific action by an inquirer. For small to medium size groups of users generating low volume traffic and unable to justify the cost of private lines, this arrangement provides expensive but ubiquitous access to a database. Because of the high cost per transaction associated with this arrangement, certain groups of users in low profit margin businesses, such as small retailers, cannot afford this solution and therefore may refuse to accept any form of payment requiring credit authorization. Other operational drawbacks of this arrangement include the long call setup time needed to complete the transaction and the unsecure access which makes the system vulnerable to security breaches by intruders.